The present invention relates generally to a backup of information stored on a storage system and more particularly to server-free backup of information on a storage area network (SAN).
With the increasing complexity of applications and the use of enormous amounts of information, the traditional model of servers controlling their storage devices has evolved into a Storage Area Network (SAN) model where the back-end storage functions are decoupled from the front end server applications. The servers and storage systems are connected together via high speed fiber-optic networks, i.e., Fibre Channels, and communicate using a Fibre Channel Protocol (FCP). The Fibre Channel paths are determined by high speed Fibre Channel Switches.
One major problem with a SAN was that the servers were still responsible for backup of their data. Thus a server needed to read in its data from a storage device, such as a disk system, and write it to a backup device, such as a tape or DLT library. With the present use of multi-terabyte databases, the backup function seriously reduced performance of the servers.
One prior art method of having a server-free backup was to off load the control of the storage system backup to the Fibre Switches (see the white paper, xe2x80x9cDeliver Server-Free Back-up,xe2x80x9d April 2000, Pathlight Technology, Inc., Ithaca, N.Y.). FIG. 1 shows such a prior art system that uses a Fibre Channel Switch to perform the back-up after receiving a command from the host or server. FIG. 1 shows a server 110 coupled to its storage system, i.e., disk system 114, via a SAN having Fibre Channel Switch 112. A Tape Library 116 which is used for backup is also connected to Fibre Channel Switch 112 via a Fibre channel. The server 110 issues an Extended Copy (E-Copy) command 118 to a Fibre Channel Switch 112. The E-Copy is a SCSI Primary Command 2 or a vendor specific command, such as from Legato (copyright) Systems, Inc. of Mountain View Calif. (referred to herein as Legato (copyright)) that instructs the copying of data from one logical device to another logical device. A copy manager in the Fibre Channel Switch 112 upon receiving the E-copy command from the Server 110 performs the Data transfer 120 by copying data from Disk System 114 to Tape Library 116. The copying proceeds under control of the Fibre Channel Switch 112 without need of server 110 action. Thus the server 112 is free to perform other tasks.
However, the above method of using the Fibre Channel Switches to control the back-ups also has problems. The Fibre Channel Switch 112 sends a read command to the disk system to retrieve back-up data. In addition the server 110 may also send a read command to the Disk System 114 to retrieve data for use in a user application. From the view point of the disk system 114, the disk system may not be able to distinguish between a read from the server 110 and a read for backup from the Fibre Channel Switch 112, thus the Disk System 114 may process both read commands with equal priority. However, the Disk System 114 should process the server read command before the less critical back-up read command.
In addition having the Fibre Channel switch 112 responsible for the heterogeneous disk system backups on a SAN leads to a complicated switch. Also the installed switches must all be compatible and may be required to be from only one vendor. And when the software or hardware on a disk system is modified or upgraded, the backup function of the Fibre Channel switch 112 may need to be changed. Thus using the Fibre channel switch as a back-up controller increases the equipment cost/complexity and maintenance burden.
Thus there is a need for an improved backup technique which further decentralizes the back-up of a storage system on a SAN to, for example, the storage system itself.
The present invention provides a method, a system and code for backing up information on a storage system, for example, a disk system, connected to a storage area network. The host or server system off loads the task of backing up its data to the storage system that stores the data. In an exemplary embodiment a server sends an E-Copy command to a copy manager on a disk system. Next, the copy manager finds an available back-device, for example a tape or DLT library, and then backups the information indicated in the E-Copy command to the back-up device. A user interface is provided so that one or more path groups, comprising at least a target port and an initiator port, on a disk system may be designated.
In one embodiment of the present invention a method for copying information from a storage system to a backup system of a plurality of backup systems is provided. The storage system is coupled with the plurality of backup systems via a storage area network (SAN). The method includes the storage system receiving a command to copy the information, from the server. Next, the storage system finds an available backup system; and under control of the storage system, the information is copied to the available backup system.
In another embodiment of the present invention a system for server free back up of information on a storage area network is provided. It includes a server system for sending a command to backup the information; a plurality of back-up systems; and a storage system including the information and responsive to the command, finding an available back-up system of the plurality of back-up systems for backing up the information to, where the storage system is coupled with the server system and the plurality of back-up systems.
In yet another embodiment of the present invention a storage system for executing an Extended Copy (E-Copy) command from a server is provided. The storage system is coupled with a plurality of back-up devices over a storage area network, including: a disk for storing data from the server. There is a target port for receiving the E-Copy command, including a parameter list, where the parameter list lists the data for backup to a back-up device port; and there is an initiator port responsive to the E-Copy command for connecting to the back-up device port on the storage area network to backup the data to the backup device.
In a further embodiment of the present invention a RAID system for executing an E-Copy command from a server system, includes: a plurality of disk units for non-volatile storage of data and at least one disk controller system coupled to the plurality of disk units for receiving and executing the E-Copy command from the server. The disk controller system includes: a target port coupled to a first microprocessor, the port receiving the E-Copy command from the server; an initiator port coupled to a second microprocessor, the initiator port for connecting to a target port of a backup device; and a shared memory coupled to the first and second microprocessors for exchanging E-Copy command information; and the disk controller system executes the E-Copy command without need for intervention from the server system.
Another embodiment provides a method for a storage system of backing up the storage system""s data according to an extended copy instruction received from a host computer, the method includes; responsive to the extended copy instruction creating a bitmap table stored in memory; concurrently polling the memory by a plurality of concurrently running processors; when a processor of the plurality of concurrently running processors is in the bitmap table, connecting to a backup device in a storage area network; when the connecting is successful backing up the storage system""s data to the backup device.
These and other embodiments of the present invention are described in more detail in conjunction with the text below and attached figures.